Metabolic Disorders: PORPHYRIN DISORDERS Flashcards
PORPHYRIN DISORDERS
• Solubility of porphyrin compounds varies
• ALA, porphobilinogen, and uroporphyrin are the most soluble
•______ is less soluble but still can be found in urine (stool may be used)
•_______ is not seen in urine (stool may be used)
•____ is a more acceptable specimen to avoid false-positive results
Coproporphyrin
Protoporphyrin
Bile
PORPHYRIN DISORDERS
• porphyrin precursors (porphobilinogen and S-aminolevulinic acid) and the porphyrinogens (uroporphyrinogen, coproporphyrinogen, protoporphyrinogen)
are________,_______ compounds
colorless
nonfluorescent
Porphyrin
their oxidative forms (uroporphyrin, coproporphyrin, protoporphyrin) are________
dark red or purple and intensely fluorescent
• is an indicator of possible porphyria
Red or port wine urine color
PORPHYRIN DISORDERS
• Disorders that result in accumulation of the precursors (______ and______) present with primarily neurologic symptoms, because these substances are neurotoxins
porphobilinogen and
d-aminolevulinic acid
when porphyrins are the major accumulation products,______ is the distinguishing clinical feature.
photosensitivity
• When______ absorb light, they cause toxic free radicals to form; this causes cutaneous lesions (e.g., extensive blistering or bullous lesions) or a burning sensation with an inflammatory skin reaction.
porphyrins
VAMPIRES AND PORPHYRIA
• Photosensitivity
• Pale color
• Port wine urine/red-stained teeth
• Psychiatric symptoms
• Inherited disorder
PORPHYRIN DISORDER TESTS
NAME OF TEST
• 2 drops urine + 2 mL Hoesch reagent
• Observe the top of the solution for the appearance of a red color
• Shake the tube
• Red color is seen throughout the solution, indicating the presence of porphobilinogen
• Sensitive to porphobilinogen but subject to many false-positive reactions
• Hoesch Screening Test for Porphobilinogen
PORPHYRIN DISORDER TESTS
• Hoesch Screening Test for Porphobilinogen
• 2 drops urine + 2 mL Hoesch reagent
• Observe the top of the solution for the appearance of a_____ color
• Shake the tube
• Red color is seen throughout the solution, indicating the presence of______
• Sensitive to______ but subject to many false-positive reactions
red
porphobilinogen; porphobilinogen
WATSON-SCHWARTZ TEST
• Soluble to chloroform and butanol
• Red color in chloroform layer and butanol layer
• Urobilinogen
WATSON-SCHWARTZ TEST
• Insoluble to chloroform and butanol
• Red color remains in the urine-acetate mixture
• Porphobilinogen
WATSON-SCHWARTZ TEST
• Insoluble to chloroform, soluble to butanol
• Red color in urine-acetate layer in chloroform tube, butanol layer in butanol tube
• Other Ehrlich-reactive substance
are intermediate compounds in the production of heme (oxygen-carrying component of hemoglobin).
Porphyrins
🧪 Porphyrin Precursors (2)
• α-Aminolevulinic acid (ALA)
• Porphobilinogen (PBG)
Disorders of porphyrin metabolism are collectively called_____ and can be inherited or acquired.
porphyrias
🔬 Fluorescence under UV light (_______range)
• Detects uroporphyrin, coproporphyrin, and protoporphyrin.
• More specific than the Ehrlich reaction.
550–600 nm
🔬_______ Test
• Differentiates urobilinogen from porphobilinogen (PBG).
Watson-Schwartz
🔬_______ Test
• Rapid test for porphobilinogen.
• Most useful during acute attacks of porphyria.
• Increased porphobilinogen = Acute intermittent porphyria.
Hoesch
